Ab NK (CD56/16) refers to the antibody staining of natural killer (NK) cells to detect the presence of specific surface markers, CD56 and CD16. CD56 is a neural cell adhesion molecule, and CD16 is an Fc receptor. Ab NK (CD56/16) analysis is crucial in identifying and characterizing different subsets of NK cells, including the CD56bright and CD56dim populations, each with distinct functional roles in the immune system.

The Aβ42/40 Ratio (Amyloid Beta 42/40 Ratio) is a biomarker that helps detect early signs of Alzheimer’s disease by measuring the balance between two key amyloid beta proteins in the blood or cerebrospinal fluid. A lower ratio indicates a buildup of amyloid plaques in the brain, one of the earliest and most specific signs of Alzheimer’s pathology—even before symptoms appear. This test is particularly useful for individuals experiencing memory loss or at risk of cognitive decline, and it is often used alongside tau protein markers to improve diagnostic accuracy and guide early intervention.

The biomarker Abnormal Protein Band 1 is part of a blood test called "Protein Electrophoresis". 

Protein electrophoresis is a test that measures specific proteins in the blood. The test separates proteins in the blood based on their electrical charge. The protein electrophoresis test is often used to find abnormal substances called M proteins (the M stands for "monoclonal").

The "Abs. CD 8 Suppressor" biomarker in a T + B-Lymphocyte Differential panel from Labcorp measures the absolute count of CD8 positive suppressor T-cells in the blood. CD8 cells, also known as cytotoxic T cells, play a critical role in the immune system's defense against pathogens and cancer cells by directly destroying infected or malignant cells. The absolute count provides a specific numeric value of these cells, unlike percentage values which only give a proportion relative to other cells.

The biomarker "Abs.CD19+ Lymphs" in the T + B-Lymphocyte Differential panel from Labcorp measures the absolute count of CD19 positive lymphocytes, which are primarily B cells. CD19 is a marker indicating B cell presence, crucial for the adaptive immune response, especially in antibody production. This absolute count provides a specific numerical value rather than a percentage, offering a direct measure of the B cell population in the blood. It's instrumental in diagnosing and monitoring conditions affecting B cell function, such as immunodeficiency disorders, certain types of leukemia, and autoimmune diseases. Understanding variations in these counts is vital for evaluating the immune system's health and function.

CD25 is the receptor for IL2 and is expressed on activated T cells, B cells, and macrophages. CD25 is expressed in certain types of B-cell lymphoma (hairy cell leukemia) and T-cell lymphoma (adult T-cell lymphoma/leukemia [ATLL]).

Why use the CD57 test?

The CD57 test is offered in some clinical laboratories and is being used by some health practitioners to evaluate and follow patients diagnosed with chronic Lyme disease.

What is Lyme disease?

Lyme disease, the most common vector-borne illness in the United States, is caused by Borrelia burgdorferi and transmitted by the bite of the Ixodes sp. tick (the deer tick).

The disease usually begins with erythema migrans, an expanding skin lesion at the site of the tick bite. Within several days or weeks, there is hematogenous dissemination of the spirochetes, and patients may present with dermatologic, neurological, cardiac, and rheumatologic involvement.

CD3 is a protein complex on the surface of mature T-lymphocytes, and laboratories use it to recognize a T cell. The absolute CD3 count is therefore a headcount: how many T cells are in a microliter of blood.

Check the scale before anything else. LOINC lists #/mm3, /uL and 10^9/L for this analyte. The first two are identical; multiply a 10^9/L figure by 1,000 to get /uL, so 1.5 x10^9/L is 1500 /uL.

The stored range is one laboratory's. 622 - 2402 /uL matches Labcorp's published adult interval for test 096917. A 2021 study of 496 healthy adults reported 834.47–2,216.8 cells/µL, so read the range printed on your own report.

The panel exists to classify primary immunodeficiency and to monitor HIV. In HIV it is CD4, not CD3, that stages disease — the CDC's 2014 case definition does not mention CD3 at all.

What the count does not do matters as much. It does not say which subset is affected, it does not measure how well the cells work, and "CD3-positive" on a report means the cells are T cells, not that they are malignant.

The absolute CD3 count measures the total number of CD3-positive T lymphocytes in the blood. CD3 is a protein complex present on the surface of all T cells — it is the universal T cell marker. The normal adult range is approximately 622–2,402 cells/µL, though laboratory reference ranges vary. A high absolute CD3 count (CD3 lymphocytosis) most commonly reflects viral infection, immune activation, or inflammatory conditions. A low absolute CD3 count (CD3 lymphopenia) may indicate HIV infection, immunodeficiency, or immune suppression from medications or illness. The absolute CD3 count is always interpreted alongside CD4, CD8, and the total lymphocyte count.

The CD4 cells are Helper T-cells expressing both CD3 and CD4.

CD4 T-cells levels are a criterion for categorizing HIV-related clinical conditions by CDC's classification system for HIV infection. The measurement of CD4 T-cell levels has been used to establish decision points for initiating P. jirovecii prophylaxis, antiviral therapy and to monitor the efficacy of treatment. The Public Health Service (PHS) has recommended that CD4 T-cell levels be monitored every 3 to 6 months in all HIV-infected persons.

During HIV infection, antiviral therapy is often initiated when the absolute CD4 count drops below 500 cells/µL. When the absolute CD4 count drops below 200 cells/µL, therapeutic prophylaxis against PCP and other opportunistic infections may be initiated. When the absolute CD4 count drops below 100 cells/µL, prophylaxis against Mycobacterium avium complex is recommended.

The CD4 cells are Helper T-cells expressing both CD3 and CD4.

CD4 T-cells levels are a criterion for categorizing HIV-related clinical conditions by CDC's classification system for HIV infection. The measurement of CD4 T-cell levels has been used to establish decision points for initiating P. jirovecii prophylaxis, antiviral therapy and to monitor the efficacy of treatment. The Public Health Service (PHS) has recommended that CD4 T-cell levels be monitored every 3 to 6 months in all HIV-infected persons.

During HIV infection, antiviral therapy is often initiated when the absolute CD4 count drops below 500 cells/µL. When the absolute CD4 count drops below 200 cells/µL, therapeutic prophylaxis against PCP and other opportunistic infections may be initiated. When the absolute CD4 count drops below 100 cells/µL, prophylaxis against Mycobacterium avium complex is recommended.